1. The influence of differences in the nature of the intermolecular forces in different solvents on their solvent powers has been examined. 2. A graphical method is proposed for evaluation of the influence of the nature of the intermolecular forces of the solvent on the maximum swelling of vulcanizates. 3. For a given rubber and a given chemical class of solvents, the relationship between δs and (μ−μs)òVs is linear. Lines for different classes of solvents intersect at one point which represents δr, the solubility parameter for the rubber.